This invention relates to ring binders. As used herein, the term "ring binder assembly" means an empty folder or book having a spine, in combination with a metal ring mechanism attachable to the spine. A typical ring mechanism comprises a metal shell riveted along the spine, a pair of hinged leaves retained in compression by the shell, and opposed half-rings attached to both leaves in such a way that the half-rings can be snapped closed to retain punched papers in the binder.
A ring mechanisms of the sort contemplated by this invention is shown and described in U.S. Pat. No. 4,552,478, the disclosure of which is incorporated into this specification.
Ring binders such as the well-known three-ring binder are normally permanently assembled at the factory, then boxed and shipped. A consequence is that, particularly for binders having wide spines, shipping density is low: even though the binders are alternated in direction as they are packed in cartons, most of the volume of the cartons is air. Because low shipping density results in high transportation costs, and shipping costs are a large part of the delivered cost of ring binders, it would be advantageous to achieve higher shipping densities.